The invention pertains to slings for supporting the arms or patients, especially those who have suffered injury or disability, possibly caused by a stroke, which has resulted in paralysis of one side (hemiplegia).
Paralysis of one side, or hemiplegia, causes a number of problems related to the arm of the patient. The lack of muscle control can lead to separation of the shoulder joint (subluxation) if the arm is not properly supported. Swelling (edema) results in those lower parts of the limb, especially the hand and fingers, in which the blood tends to pool. The shoulder may "roll in" or turn forward (protraction).
Prior art slings intended for sprains or fractures do not prevent any of these problems. (see, e.g. U.S. Pat. Nos. 3,730,164 to Rash, or 2,539,677 to Teale). Those slings most commonly supplied to stroke victims are heavy, uncomfortable, and difficult to put on. They tend to restrict the movement of the affected limb to a great extent, leading to discomfort and difficulty in balance. The hand is allowed to droop in a palm-down position (pronation). This is unnatural and leads to edema in the fingers, and to other ill effects due to pinching of nerves and blood vessels.
U.S. Pat. No. 4,214,579 issued in 1980 to Ford, shows one such prior-art sling, and is illustrative of the problems common to most such appliances. The arm is supported by a rigid plastic holder, which adds to the complexity, expense, weight and discomfort of the sling. Common to many such devices, the support strap passes directly over the patient's shoulder to the hand. This can be extremely uncomfortable for women, with one breast compressed by the strap. The complexity makes the design difficult for stroke victims to put on without aid. The constant pressure of the rigid support can lead to discomfort and sores. Ford makes an attempt to avoid the pronation present in earlier designs (see, e.g. Sanders U.S. Pat. No. 2,594,809), at the cost of additional complexity and custom molding. The shoulder is not well protected from subluxation. Lausner, U.S. Pat. No. 3,815,588, shows another example of this rigid-type sling, having much the same drawbacks as Ford.